Core drill



L. S. COPELIN Feb. 6, 1940.

CORE DRILL Filed Deo. 11. 1937 2 Sheets-Sheet l ATTORNEY.

Feb. 6, 1940.

L. S. COPELIN UORE DRILL Filed Dec. 11, 1937 2 Sheets-Sheet 2 INVENTQR.

U Y. w e o www L .A 5, ,d a m@ Patented Feb. v6, 1940 1UNITED STATES PATENT OFFICE CORE DRILL Leonard S. Copelin, Los Angeles, Calif.

Application December 11, 1937, Serial No. 179,329

13 Claims. (Cl. Z55-72) This invention relates generally to the con.-

struction of so-called core drills, which enable one to take samples of the formation through Which the drill bit is passing, as the boring of i a well proceeds. More particularly this invention relates to core drills of the type having a core barrel or retainer which can be introduced intoor withdrawn from the drill stem, without removing the drill stem and cutter from the well hole. Such devices are commonly known as wire line core drills, since the core barrel is removed with respect to the drill stem by use of a wire line, carrying a suitable grappling tool at its lower end.

15 In the past core drills of the above type haveA been subject to certain disadvantages. Briey they have made use of complicated latch mechanisms, to lock the removable core barrel assembly in operating position, whereby locking engagement or dis-engagement can occur automatically, as the core barrel assembly is lowered into operating position or lifted by a wire line. Also during normal drilling operations, drilling mud being circulated under high pressure down through the main drilling stem, has in part circulated into direct contact with the core, to cause in many instances disintegration or serious erosion of the core, or impregnation of the core with cuttings.

It is an object of the present invention to devise a core drill of the above type, which will avoid the use of complicated latch mechanism, for locking the core barrel assembly in operative position. In this connection the invention is characterized by the use of the pressure of drilling mud being pumped down through the drill stem to hold the c'ore barrel assembly in operating position. i

A further object of the invention is to pro- 40 vide a core drill which will prevent direct circulation of ydrilling mud into engagement with the core being taken, whereby the core tends to remain intact, and is properly representative of the formation from which it is taken,

Additional objects of the invention will appear from the following description in which the preferred embodiment of the invention has been set forth in detail .in conjunction with the accompanying drawings. g

Referring to the drawings: f I

Figs. la. and 1b, when taken together, constitute a side elevational View, partly in crosssection, of a core drill incorporating the'present invention, Fig'. 1a showing the lupper portion of the drill, and Fig. 1b the lower portion carry- The core drill as illustrated in the drawing consists of a tubular drill stem I0, the lower end of which carries a cutter head II. The head .II is of some suitable type, provided with cutting teeth I2, and including a central opening 5 I3 through which a core may pass. The shank of the cutter head is shown attached to the lower end of the drill stem, by a threaded connection I4. As well understood by those familiar with equipment for drilling oil or gas wells, the drill 10 stem I0 extends to the top of the well, where it is engagedy by a rotary rig for drilling operations. I

Disposed within the lower portion of the drill stem I0, are the inner and outer core barrels l5 I6 and Il. These barrels are disposed one within the other, and they are generaly aligned \--fith the axis of the drill. The inner barrel 6 forms a core receiving compartment I, extending upwardly above the core passage I3 The lower 20 end of the outer core barrel I1' is xed to the cutter II, as by means'of the threaded con" nection I9. The upper ends of both the inner and outer barrels have a special form of sealed connection, whereby the inner barrel is supported entirely by the outer barrel, and whereby drilling mud being forced downwardly under pressure through the drill stem, exerts pressure tending to maintain such sealed connection.

The sealed connection referred to above is formed by a number of parts connected to the upper ends of the barrels, and including par-A ticularly thetubular body 2|, and head 22. The lower end of body 2I is shown attached to the upperend of the outer barrel I1, as by means 35 of a threadedconnection 23. The upper portion of the body 2| has a peripheral surface 24 of enlarged diameter, which is only slightly smaller in diameter than the internal diameter of the drill stem I0. Thus drilling mud being 40 pumped downwardly under pressure through the drill stem, for delivery to the cutter head, must pass downwardly through the passage 26 in body 2|, through the ports 21 in this body, and from thence down through the space 28 aorded `be- 45 tween the drill stem and the outer barrel I 1. Ports 29 in the cutter head serve to ydeliver the drilling mud from passage 28 to the cutting teeth. Below the level of ports 2'I there is an annular seat 3,I formed in body 2|. The head l22, which 50 occupies the position illustrated in Figs. 1a during core drilling operations, is. provided with an .annular Asurface 32 adapted. to have abutting sealing engagement with surface 3|. 'Ihus the head 22 forms a closure for the `lowerfzend of 55 the body 2|, below the ports 21. The lower or inner end of the head 22 connects to the upper end ofv the inner core barrel I6, preferably through a swivel connection, whereby the inner barrel or retainer is free to rotate about its axis.

'Ihus a stud 33 is shown attached to the lower end of the head 22, and this stud connects with the upper extension 34 of a valve body 36, through the ball bearing assemblies 31 and 38. 'I'he body 36 is in turn coupled to the upper end of the inner barrel I6, as by means of a threaded connection 39. yThe upper end of the core compartment I8 is in communication with the space 4| between the inner and outer barrels, through passages 42 and 43, which are controlled by the ball check 44.

The upper end of the head 22 is provided with an extension 46, adapted to be detachably engaged by a suitable grappling tool. The upper face of the body 22, including portion 46, forms an effective uid pressure area, against which the pressure of the drilling mud acts as this mud is being pumped downwardly through the drill stem. Thus during normal drilling operations the head 22 is forcibly urged downwardly to retain it firmly seated in the position illustrated, with surfaces 3| and 32 in sealed abutting engagement.

While the force of the drilling mud prevents dislodgment of the head 22 during drilling operations, there is a possibility that the head may become dislodged during periods when no mud pressure is present, or during times when a back pressure may be exerted upwardly upon the head, as for example when the assembled drill is being lowered into a well. To prevent such accidental dislodgment, it is desirable to provide some form of detent, tending to lock the head in operative position. For example the head is shown provided with a slidable plunger 48, urged outwardly by the compression spring 49. The outer end of this plunger carries a shear pin 5|, adapted to engage in an annular recess 52, formed within the body 2|. Shear pin 5| will readily snap into the annular recess 52, as the head is being lowered into the body 2|. However, after such engagement has been established, accidental dislodgment will be prevented. If suflcient upward force is exerted upon the head by an upward pull upon a wireline engaged with the head, the shear pin 5| can be broken to permit lifting o1' the head and the attached inner core barrel.

Reference has been made to the passages 42 and 43 for venting the upper portion of the core compartment. The purpose of these passages is to permit ready venting of liquid from the core compartment as the core progresses into the inner barrel |6, thus avoiding any undue downward pressure upon the core. Any liquid so vented into the space 4|, between the inner and outer core barrels, is separately vented from the lower .end of space 4 I, through ports 5 3 in the cutter head.'

The lower end of the inner core barrel I6 is provided with a suitable form of core catcher, to facilitate severing a core and to retain the core within the inner barrel while this barrel is being lifted upwardly to the surface of the well. Thus in the embodiment illustrated, the lower ena of the barrel I6 'is provided with a cenar 5I,

which in turn carries the inwardly extending spring ngers 56.

Use of the core drill illustrated in Figs. 1a and 1b, can be outlined as follows: During drilling operations, to take a core from the formation upon which the drill is operating, the parts are assembled as illustrated in Figs. 1a and 1b. Drilling mud being pumped downwardly through the drill stem, under considerable pressure, ows through passage 26, ports 21. passage 28-between the drill stem and the outer core barrel, and from thence through the cutter head. Considerable hydraulic pressure is exerted upon the upper end of the head 22, so that this head is firmly held down in its proper operating position, and in assembled relationship with respect to the outer core barrel. VAside from the manner in which pressure of the drilling mud is applied to hold down the head 22, this circulation is not permitted to contact a core within the inner core barrel. As the core advances into the inner core barrel, it is engaged by the core catcher ngers 56, and such engagement, together with any frictional engagement between the inner barrel to remain stationary, while the drill rotates. As the formation advances, any liquid displaced from compartment I8 may ilow upwardly through passages 42 and 43, and downwardly through passage 4| between the inner and outerbarrels, to be finally vented through ports 53. Discharge at this point into the region of the cutter head is a discharge to a point of relatively low hydraulic pressure, compared to the pressure of drilling mud as it is being pumped downwardly through the drill stem. After a core has been formed, rotation of the drill stem is interrupted and a wire line carrying a suitable grappling tool, is lowered through the stem and engaged with the head portion 46. As the head is pulled upwardly shear pin 5| is broken to permit disengagement with the body 2|, and the head together with the inner core barrel and enclosed core, is now lifted to the surface of the well. After the core has been removed, and a new shear pin 5| applied, the inner core assembly can again be lowered through the drill stem, and seated upon the body 2|, in the manner illustrated in Figs. la and 1b.

Figs. 2 and 2b illustrate an arrangement where it is desired to carry on drilling operations without taking a core` In this instance the inner core barrel assembly has been removed, and replaced by an assembly carrying a small bit which projects from the core passage I3. Thus in this instance the assembly which takes the place'of the inner core barrel and head 22, includes a head 6|, the inner end of whichis coupled to a tubular stern 62. The lower portion of stem 62 projects through the core passage I3, and carries a small bit 63 on its lower end, as for example a bit of the sh-tail type. The head 6| is constructed somewhat similar to the head 22 of Fig. 1a, but instead of serving as a closure it is provided with a central passage 64 and ports 66, whereby a part of the drilling mud can flow down through the stem 62, to the sh-tail bit 63. In order to rotate the stem 62 together with the main drill stem, stem 62 carries a retractable key 68, adapted to engage a lug 69 carried on the inner wall of the core barrel |1. Key 68 is mounted in a slot 1|, formed in the side of drill stem 62, and is urged towards projected position by compression springs 12. Thus in lowering this assembly into the main drill, key 68 is retracted to pass through the body 2|, andy when positioned asv illustrated in Fig. 2b, it is proq jected by springs 12, to engage the lug 69. It to be understood that at any time the head 6| and its connected bit can be withdrawn and the inner core ba'rrel assembly of Figs. 1a and 1b, substituted, for core drilling operations. Ports 66 are comparatively restricted, so that although a certain amount of drilling mud is permitted to ilow down through the inner stem 62, a sumcient hydraulic pressure is exerted upon the upper surface of head 6|, to retain this head in position and' I6 to hold down the center fish-tail bit 63, against the formation.

It will be evident that the core drill described above obviates the necessity of utilizing special latching means for holding the inner core barrel in position, and therefore the mechanical conl struction is materially simplified, and 'operation made more reliable. Not only is the inner core barrel assembly held in position by the pressure of the drilling mud, but in addition the drilling mud being pumped down through the main drill stem is not permitted to circulate directly into engagement with the core, and therefore the core will not be subject to erosion, nor will it be impregnated with drilling mud or cuttings.- Therefore cleancut/and full sized cores can be taken from various formations, so that an operator can be assured of a true sample of the various geological formations through which the well is being bored.

I claim:

1. In a rotary core drill, a tubular drill stem, a cutter carried by the lower end of the drill stem, said cutter being adapted to form a central core, a core barrel within the drill stem and adapted to receive a core as formed by operation of the cutter, and means utilizing hydraulic pressure of drilling mud pumped down through the drill stern for retaining and supporting the' core barrel in operative position, said last means including a head swivelly connected to the upper end of the core barrel and removable upwardly through the drill stem, the swivel connection between the barrel and the head forming the sole support for the barrel an enabling relative turning movement between the stem and the barrel.

'2. In a rotary core drill, a tubular drill stem, a cutter carried by the lower end of the stem, the cutter having a central core passage, inner and outer core barrels disposed within the drill stem above the cutter, both said barrels being aligned with respect to the axis of the drill and being disposed one within the other, means forming a sealed connection between the upper end portions of the two barrels, said means forming a swivel support for the inner barrel, there being a space between the drill stem and the outer barrel for downward flow Aof drilling mud to the cutter, there being a space between the outer and inner barrels which is in communication with the upper end of the core receiving compartment of the inner barrel, said connection serving to isolate said space with respect to the downward iiow of drilling mud to the cutter, the lower end of the inner barrel being freerof supporting engagement with respect to the cutter and outer barrel.

3. In a rotary core drill, a tubular drill stem, a cutter carried by the lower end ofthe stem, the

cutter having a central core passage, inner and outer core barrels disposed within the drill stem above the cutter, both said barrels being aligned with respect to the axis of the drill and being disposed one within the other, means forming a fixed mounting between the lower end of the outer barrel and the cutter, `means forming a detachable connection between the upper end of the cutter core barrel and the upper end of the inner core barrel, whereby the inner barrel is supported by the upper portion of the outer barrel, there being a space between the drill stem and the outer barrel serving vto; convey drilling mud downwardly to the cutter, there being a space between the vinner and outer core barrels which is in communication with the upper end s of the core compartment vformed by the inner barrel and also with the core passage at the lower end of the inner barrel, the connection between the inner and outer barrels serving to isolate the space between said barrels and the core compartment, with respect to the downward flow of drilling mud.

4. In a rotary core drill, a tubular drill stem, a cutter carried by the lower end of the drill stem, the cutter having a central core passage, inner and outer corebarrels disposed within the drill stem above the cutter, bothsaid barrels being aligned with respect to the axis of the drill and also being disposed one within the other, the lower end of the outer barrel being mounted upon the cutter, there being a space between the drill stem and the outer core barrel, anda space between the inner and outer core barrels, and means forming a detachable sealed connection between the upper end portions of the inner and outer core barrels, said last means including a head swivelly connected with the upper end of the inner core barrel, the inner barrel being unsupported except for its connection to said head, and a body secured to the upper end of the outer core barrel, and formed to afford an upwardly faced annular seat engaged by the head to form a nongripping sealed engagement, whereby the head together with the inner barrel can be lifted upwardly by a direct upward pull applied to the head, said head affording an area exposed to the pressure of downwardly flowing drilling mud, whereby such pressure tends to urge said head against said seat.

5. In a rotary core drill, a tubular drillstern, a cutter carried by the lower end of the drill stem, the cutter having a central core passage, inner and outer core barrels disposed within the drill stem above the cutter, both said barrels being aligned with respect to the axis of the drill and also being disposed one within the other, the lower end of the outer barrel being mounted upon the cutter, there being a space between the drill stem and the outer core barrel and a space betwen the inner and outer core barrels, and means forming a detachable sealed connection between the upper end portions of the inner and outer core barrels, said last means including a head connected with the upper end of the inner core barrel, the inner barrel being unsupported except for lsaid connection` to the head, and a body secured to the upper end of the outer core barrel and formed to provide an upwardly faced annular seat engaged by the head to form a nongripping sealed engagement, whereby the head together with the inner barrel can be lifted upwardly by a direct pull applied to the head, said body being formed to afford ports located above said head to convey substantially the entire flow of drilling mud from the drill stem into the space between the drill stem and the outer core barrel, said head also affording an area exposed to the pressure of downwardly flowing drilling mud, whereby such pressure tends to urge said head against said seat.

6. In a rotary core drill, a tubular drill stem, a cutter carried by the lower end of the stem, the cutter having a central core barrel, inner and outer core barrels disposed within the drill stem above the cutter, both said barrels being aligned with respect to the axis of the drill and being disposed one within the other, there being a space between the drill stem` and the outer core barrel, and another space between the inner and outer core barrels, the inner core barrel forming a core receiving compartment extending upwardly from outer core barrel and the cutter, and means forming a detachable sealed connection between the upper ends of the inner and outer core barrels,

said last means including a tubular body secured to the upper end of the outer core barrel, a portion of the outer periphery of said body being of a diameter only slightly less than the internal diameter of the drill stem adjacent said periphery, the opening to said body affording a passage for downward ow of drilling mud, ports in said body serving to convey drilling mud from said passage to the passage between the drill stem and the outer core barrel, said body affording an annular seat on a level below said ports, a head adapted to belowered into said body, said head being provided with an annular surface adapted to have sealed abutting engagement with the annular seat formed on the body, and means forming a connection between said head and the upper end of the inner core barrel.

7. In a rotary core drill, a tubular drill stem, a cutter carried by the lower end of the drill stem, the cutter having a central core passage, inner and outer core barrels disposed within the drill stem above the cutter, both said barrels being aligned with respect to the axis of the drill and being disposed one within the other, means forming a connection between the lower end of the outer core barrel and the cutter, whereby the outer barrel turns together with the drill stem, there being a passage between the drill stem and the outer core barrel, a generally tubular shaped body secured to the upper end of the outer core barrel, the upper portion of said body being of a.

diameter only slightly less than the adjacent internal diameter of the drill stem, said body forming a passage for downward flow of drilling mud being introduced into the upper end of the drill stem, ports in said body to convey drilling mud from said passage into the passage between the drill stem and the outer core barrel, ,ports in the cutter whereby drilling mud is conveyed from the lower end of said latter passage, to the cutting surfaces, said body being also formed to provide an annular seat below the location of said iirst named ports, a head adapted to be lowered into said tubular body, said head having an annular surface adapted to have sealed abutting engagement with the annular surface formed on the body, whereby said head forms a seal for the lower portion of said body and is urged in a direction to force the said irfaces into sealing engagement by the pressure of drilling mud .being forced downwardly through the drill stem, means forming a swivel connection between said head and the upper end of the inner core barrel, whereby the inner core barrel'is free to rotate about its axis, means for venting fluid from the upper end of the core compartment formed by the inner core barrel, into the space between the inner and outer core barrels, and means for venting the lower end of the space between the inner and outer core barrels.

8. In a rotary drill, a tubular drill'stem, 'a cutter secured to the lower end of the drill stem, the cutter having a central core passage, a core barrel carried by the cutter and aligned with the axis of the drill stem, a head removably seated upon the upper end of the core barrel, said head being adapted to be held down on the core barrel by the pressure. of drilling mud pumped down through the drill stem, anda bit carried by the head and extending through said core passage.

9. In a rotary drill, a tubulardrill stem, a cutter secured to the lower end of the drill stem, the cutter having a central core passage, a core barrel carried by the cutter and aligned with the-axis of the drill stem, a head removably seated upon the upper end of the core barrel, said head being adapted to be held down on the core barrel by the pressure of drilling mud pumped down through the drill stem, an inner stem having its upper end secured to the head, a bit secured to the lower end of the inner stem and extending through vsaid core' passage, and means carried by saidinner stem for causing the bit to rotate in unison with the drill stem.'

10. In a rotary drill, atubular drill stem, a cutter secured to the lower end of the drill stem, the cutter having a central core passage, a core barrel carried by the cutter and aligned with the axis of the drill stem, a head removably seated upon the upper end of the core barrel, said head Abeing adapted to be held down on the core barrel by the pressure of drilling mud pumped down through the drill stem, an inner stem having its upper end secured to the head, a bit secured to the lower end of the inner stem and extending through said core passage, and,means carried by said inner stem for causing the bit to rotate in unison with the drill stem, said last means in-I cluding a retractable key mounted upon said inner stem.

11. In a rotary drill, a tubular drill stem, a cutter secured to the lower end of the drill stem and having a central core passage, inner and outer core barrels disposed within the drill stem `above the cutter, both said barrels being aligned with respect to the axis of the drill and being disposed one within the othermeans serving to secure the outer barrel for rotation in unisonv with the stem and the cutter, a head having abutting seated engagement with the 4upper end of the outer barrel and presenting a substantial pressure area to drilling mud flowing downwardly through the stem, said head being adapted for engagement with a grappling tool for removal of the same, and means forming a swivel connection between the head and the upper end of the inner barrel whereby the inner barrel is free to roo tate relative to the drill stem and the outer barrel and'whereby the inner barrel is removed together y with the head.

12. A core drill, a drill collar thereon, a protector barrel secured to said drill and projecting upwardly in said drill collar, a seat member at the upper end of said Vprotector barrel, a wire line core barrel, a head swivelly secured thereto, a shoulder on said head to t within said seat, a stationary latch ring above said seat and a latch on said head engaging beneath said ring.

13. A core drill, a drill collar thereon, a protector barrel secured to said drill and projecting upwardly in said drill collar, a seat member at the upper end of said protector barrel, fa wire line core barrel, a head swivelly secured thereto,4 a

shoulder on4 said head to t within said seat, a latch ring secured to said protector barrel andv LEONARD S. COPELIN.

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